ULTRA-FAST VELOCITY IMAGING IN STENOTICALLY PRODUCED TURBULENT JETS USING RUFIS

A method for rapidly producing velocity images is presented. This sequ ence combines a modified bipolar gradient pulse to magnitude encode th e velocity with the rotating ultra-fast imaging sequence (RUFIS) to im age the encoded spins. Velocity encoding is done in 3 msec, and RUFIS acquires 32 projections in 8 msec. The method is applied to turbulent jets associated with a 75% stenosis in a 15-mm inner diameter glass pi pe. Data is acquired upstream and downstream from the stenosis for Rey nolds numbers from 560 to 3750. In addition, a robust method of recons tructing the unobserved short time region of a free induction decay is presented and incorporated into the image processing.